Optical fiber light source based on laser excitation fluorescence

Abstract

The invention relates to a laser-based optical fiber coupling white laser light source which is characterized by comprising a laser diode, a first lens, a diffusion sheet, a wavelength conversion sheet, a second lens, a third lens, a fourth lens, an optical fiber, a laser base, a lens base, a wavelength conversion sheet fixing base, a limiting base, an adjustable connecting piece and an optical fiber fixing disc. The laser diode emits monochromatic laser under the action of impressed current, the monochromatic laser penetrates through the first lens and the diffusion sheet and then irradiates the wavelength conversion sheet, generated white light penetrates through the second lens, the third lens and the fourth lens and then irradiates the optical fiber, and uniform and efficient white light is output. The optical fiber light source has the advantages of being compact in structure, high in conversion efficiency, long in service life and the like.

Description

Technical Field

[0001] The invention relates to an optical fiber light source based on laser-excited fluorescence, which is used in the technical fields of illumination and display. Background Art

[0002] Fiber optic light source has the advantages of small size, light weight, stable signal transmission, flexible output direction, etc. It is widely used in practical applications, such as fiber optic lighting, fiber optic sensing, etc. The basic principle of fiber optic light source is to input the light emitted by the white light source into the optical fiber from one end of the optical fiber, and then output it through the other end of the optical fiber.

[0003] According to the basic law of conservation of optical etendue, the maximum luminous flux output by the optical fiber is Estimated by the following formula:

[0004]

[0005] Where Ls is the brightness of the light source; U F is the amount of fiber expansion and is determined by the following formula:

[0006] U F =(πrNA) 2

[0007] Among them, r is the fiber core radius, and NA is the numerical aperture of the fiber. Since the optical extension of the fiber is very small, the input light source needs to have a very high brightness in order to get a relatively large light output at the other end of the fiber.

[0008] Among white light fiber optic light sources, the commonly used input light sources are halogen lamps, xenon lamps and LED light sources. Traditional halogen lamp and xenon lamp fiber optic light sources have problems such as short life, high energy consumption and high heat generation. Although LED light sources have the advantages of energy saving, environmental protection, long life and high reliability, their brightness is relatively low, so the coupling efficiency with optical fiber is low, so multi-beam optical fiber coupling is usually required, which is difficult to apply to small-diameter optical fiber lighting systems.

[0009] On the other hand, the white light source based on laser-excited fluorescence uses a laser beam to excite fluorescent materials to produce white light, which has the advantages of high energy density, small luminous area, and brightness that is more than 10 times that of LED light sources. By coupling such a light source with optical fiber, efficient coupling of white light and optical fiber can be achieved, and the system also has the advantages of long life, high reliability, and small size. Summary of the invention

[0010] The present invention is a fiber optic light source based on laser-excited fluorescence. The basic principle is to use a high-brightness white light source with laser-excited fluorescence as an input light source to achieve high-efficiency coupling of white light and optical fiber. The present invention is characterized in that it includes a laser diode, a first lens, a diffuser, a fluorescence wavelength conversion plate, a second lens, a third lens, a fourth lens, and an optical fiber. Under the action of an external current, a monochromatic laser diode irradiates a light beam onto the wavelength conversion plate through the first lens and the diffuser, forming white light on its surface, and then irradiates the light to the incident end face of the optical fiber through the second lens, the third lens, and the fourth lens, and outputs the white light through the output end face of the optical fiber to form a uniform, high-brightness white light source.

[0011] Furthermore, the normal directions of the laser diode, the first lens, the diffuser, the wavelength conversion plate, the second lens, the third lens, the fourth lens, and the optical fiber are on the same axis.

[0012] Furthermore, the laser wavelength emitted by the above laser diode is between 430nm-470nm.

[0013] Furthermore, the first lens is located behind the laser diode and before the diffusion sheet.

[0014] Furthermore, the diffusion sheet is located behind the first lens and before the wavelength conversion sheet, the diffusion angle of the diffusion sheet to the laser is between 0.5° and 10°, and the thickness of the diffusion sheet is 0.3 mm to 2 mm.

[0015] Furthermore, the wavelength conversion sheet is composed of a fluorescent material film placed on a transparent substrate, with a thickness between 0.2 mm and 1 mm, and converts laser light with a wavelength between 430 nm and 470 nm into white light with a wavelength between 400 nm and 700 nm.

[0016] Furthermore, the second lens, the third lens and the fourth lens are located behind the wavelength conversion plate and before the optical fiber.

[0017] Furthermore, the core diameter of the optical fiber is between 300um and 800um, and the numerical aperture NA is between 0.2 and 0.4.

[0018] The present invention has the following beneficial effects:

[0019] (1) Compact structure: The distance between each component unit is small, the space required for the structure is small, and the overall volume of the light source is small; (2) Precise optical path: The light source and optical components are on the same axis, which makes it easy to achieve precise alignment and improve the fiber coupling efficiency; (3) High conversion efficiency: The laser has little light energy loss before reaching the wavelength conversion plate, and the white light has little light energy loss before reaching the optical fiber, which ensures the overall efficiency of the light source; (4) Long life: The driving light source is a laser diode with a life of up to 100,000 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of optical fiber structure.

[0021] Figure 2 Schematic diagram of optical fiber receiving and transmitting light.

[0022] Figure 3 Schematic diagram of the optical path system of the optical fiber light source based on laser-excited fluorescence designed for the present invention.

[0023] Figure 4 A schematic diagram of the structure of the optical fiber light source based on laser-excited fluorescence designed for the present invention.

[0024] Figure 5 Schematic diagram of the light spot on the wavelength conversion plate.

[0025] Figure 6 Schematic diagram of the energy distribution of the light spot on the wavelength conversion plate. DETAILED DESCRIPTION

[0026] Figure 1 Schematic diagram of optical fiber structure. The core diameter (101) is made of high refractive index glass with a refractive index of n 1 ; The cladding (102) is low-refractive-index glass with a refractive index of n 2 ; A buffer layer (103) and a jacket (104). Use n 0 Represents the refractive index of the surrounding environment, and the numerical aperture NA of the optical fiber is expressed as:

[0027] Figure 2 This is a schematic diagram of optical fiber receiving and transmitting light. The transmission of optical fiber relies on total reflection of light. When light encounters the core-cladding boundary, if the incident angle θ is greater than the critical angle θmax, the light will be completely reflected; if the incident angle θ is greater than the critical angle θmax, the light will be refracted into the cladding and cannot continue to be transmitted. The critical angle of the optical fiber is determined by the core refractive index and the cladding refractive index. The size of the critical angle determines the light receiving angle of the optical fiber, which is usually expressed in numerical aperture:

[0028] A higher numerical aperture allows light to be transmitted to the core diameter by approaching the axis and at a larger angle, resulting in more efficient coupling between light and optical fiber. The coupling efficiency η can be expressed as:

[0029] Where D is the beam diameter, w 0 is the mode field radius of the single-mode fiber, λ is the wavelength of the light beam, and f is the focal length of the optical system.

[0030] Figure 3 The optical fiber light source based on laser excitation fluorescence used in the present invention. Figure 3 As shown, according to the optical path adopted by the present invention, the monochromatic laser diode (301) irradiates the light beam onto the wavelength conversion plate (304) through the first lens (302) and the diffusion plate (303), forming white light on the surface of the wavelength conversion plate, and then irradiates the light beam onto the incident end face of the optical fiber (308) through the second lens (305), the third lens (306), and the fourth lens (307), and outputs the white light through the output end face of the optical fiber (308), so as to form a uniform and high-brightness white light source.

[0031] Figure 4 Based on Figure 3 The optical path design shown is a schematic diagram of the structure of the optical fiber light source based on laser excitation fluorescence. The laser diode (402) is fixed to the laser tube base (403) by a pressure ring (401), and the lens base (404), the wavelength conversion plate base (416), and the limit base (413) are fixed together to ensure parallelism. The laser beam emitted by the laser diode (402) passes through the first lens (405) and the diffusion plate (406) and irradiates the wavelength conversion plate (415) to generate white light. The second lens (414), the third lens (407), and the fourth lens (408) irradiate the optical fiber (411) to output uniform, high-brightness white light.

[0032] The second lens (414), the third lens (407) and the fourth lens (408) are used to couple white light into the optical fiber, thereby reducing spherical aberration, achieving good collimation effect, high coupling efficiency, stable structure and small system volume.

[0033] The third lens (407) and the fourth lens (408) are limited by a lens spacer (412) to ensure accuracy.

[0034] The wavelength conversion sheet (415) converts part of the monochromatic light wavelength into other wavelengths and transmits part of the monochromatic light to form a wide spectrum white light of 400-700nm.

[0035] The adjustable connecting piece (409) is fixed to the optical fiber fixing plate (410), and the position of the optical fiber (411) can be adjusted to improve the optical fiber coupling efficiency.

[0036] Further, press Figure 3 The light source was constructed and tested, and the test results are listed in Table 1. When a single laser diode with an output power of 5 W and a wavelength of 450 nm and a driving power of 13.5 W is used, the luminous flux on the wavelength conversion sheet is 700 lm. Table 1. Optical properties of white light on wavelength converter Measurement parameters unit data Current A 3 Voltage V 4.5 Luminous flux lm 700

[0037] The light spot on the wavelength conversion plate is as follows Figure 5 As shown, the spot diameter is 0.45 mm. Figure 6 It represents the energy distribution of the light spot on the wavelength conversion plate, and the dotted line part indicates that the utilization efficiency of the optical fiber used is 70%.

[0038] It should be understood by those skilled in the art that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functions and structural principles of the present invention have been demonstrated and explained in the embodiments. Without departing from the principles, the embodiments of the present invention may be deformed or modified in any way.

Claims

1. A fiber optic light source based on laser-excited fluorescence, characterized in that: It includes a laser diode, a first lens, a diffuser, a wavelength conversion sheet, a second lens, a third lens, a fourth lens, an optical fiber, a laser base, a lens base, a wavelength conversion sheet fixing base, a limit base, an adjustable connector, and an optical fiber fixing plate.

2. The optical fiber light source based on laser excitation fluorescence according to claim 1, characterized in that: The laser diode emits a laser with a wavelength between 430nm and 470nm.

3. The optical fiber light source based on laser excitation fluorescence according to claim 1, characterized in that: The first lens is located behind the laser diode and before the diffusion plate.

4. The optical fiber light source based on laser excitation fluorescence according to claim 1, characterized in that: The diffusion sheet is located behind the first lens and before the wavelength conversion sheet.

5. The optical fiber light source based on laser excitation fluorescence according to claim 1, characterized in that: The diffusion angle of the diffusion sheet to the laser is between 0.5°-10°, and the thickness is between 0.3mm-2.0mm.

6. The optical fiber light source based on laser-excited fluorescence according to claim 1, characterized in that: The wavelength conversion sheet is located behind the diffusion sheet and before the second lens.

7. The optical fiber light source based on laser-excited fluorescence according to claim 1, characterized in that: The wavelength conversion sheet comprises a transparent substrate, a reflective film and a fluorescent material in sequence.

8. The optical fiber light source based on laser-excited fluorescence according to claim 1, characterized in that: The wavelength conversion sheet converts laser light with a wavelength between 430nm and 470nm into fluorescence light with a wavelength between 400nm and 700nm.

9. The optical fiber light source based on laser-excited fluorescence according to claim 1, characterized in that: The second lens, the third lens and the fourth lens are located behind the wavelength conversion plate and before the optical fiber.

10. The optical fiber light source based on laser excitation fluorescence according to claim 1, characterized in that: The optical fiber core diameter is between 300um and 800um, and the numerical aperture NA is between 0.2 and 0.4.

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